title: Granulocyte-macrophage colony stimulating factor blockade promotes ccr9(+)  lymphocyte expansion in Nod2 deficient mice.
abstract: BACKGROUND
  Ileal involvement in Crohn's disease (CD) is associated with NOD2 mutations and granulocyte-macrophage colony stimulating factor autoantibodies (GM-CSF Ab), and GM-CSF blockade promotes ileitis in Nod2/Card15-deficient (C15KO) mice. RALDH2-expressing dendritic cells (DC) and IL-4 promote CCR9 imprinting and small bowel homing of T lymphocytes, in conjunction with CCL25 expression by ileal epithelial cells (IEC). We hypothesized that GM-CSF neutralization promotes ileal disease by modulating expression of CCL25 by IEC and CCR9 by T lymphocytes via Nod2-dependent and independent pathways.
  
  
  METHODS
  CCL25 and CCR9 expression were determined in pediatric CD patients stratified by GM-CSF Ab. Ileitis was induced in C15KO mice via GM-CSF Ab administration followed by nonsteroidal antiinflammatory drug (NSAID) exposure, and expression of CCL25, CCR9, FOXP3, intracellular cytokines, and RALDH2 was determined in IEC and immune cell populations.
  
  
  RESULTS
  The frequency of CCL25(+) IEC and CCR9(+) T lymphocytes was increased in CD patients with elevated GM-CSF Ab. In the murine model, GM-CSF blockade alone induced IEC CCL25 expression, and reduced the frequency of mesenteric lymph node (MLN) CD4(+) FOXP3(+) cells, while Card15 deficiency alone enhanced MLN DC RALDH2 expression. Both GM-CSF neutralization and Card15 deficiency were required for downregulation of MLN DC IL-10 expression; under these conditions NSAID exposure led to an expansion of IL-4(+) and IL-17(+) CCR9(+) lymphocytes in the ileum.
  
  
  CONCLUSIONS
  GM-CSF prevents ileal expansion of CCR9(+) lymphocytes via Nod2-dependent and independent pathways. CCR9 blockade may be beneficial in CD patients with elevated GM-CSF Ab.
authors.affiliation: Gastroenterology, Hepatology, and Nutrition, Children's Hospital Medical Center and the University of Cincinnati College of Medicine, Cincinnati, Ohio, USA. charles.samson@cchmc.org
authors.forename: Charles M
authors.initials: CM
authors.lastname: Samson
authors.forename: Ingrid
authors.initials: I
authors.lastname: Jurickova
authors.forename: Erin
authors.initials: E
authors.lastname: Molden
authors.forename: William
authors.initials: W
authors.lastname: Schreiner
authors.forename: Joshua
authors.initials: J
authors.lastname: Colliver
authors.forename: Erin
authors.initials: E
authors.lastname: Bonkowski
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Han
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Trapnell
authors.forename: Lee A
authors.initials: LA
authors.lastname: Denson
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D019742:Chemokines, CC / Q000235:genetics / Q000378:metabolism; D002648:Child; D003424:Crohn Disease / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007079:Ileitis / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D007124:Immunoenzyme Techniques; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D053473:Nod2 Signaling Adaptor Protein / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D054388:Receptors, CCR / Q000235:genetics / Q000378:metabolism*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; C119309:CC chemokine receptor 9; C108074:CCL25 protein, human; D019742:Chemokines, CC; D053473:Nod2 Signaling Adaptor Protein; C495945:Nod2 protein, mouse; D012333:RNA, Messenger; D054388:Receptors, CCR; D016753:Interleukin-10; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D000445:Aldehyde Oxidoreductases; C470579:RALDH2 protein, mouse